Abstract: Some new theory and methods for development of slope rock block stability analysis system are presented in this paper. Being different from others, in the theory a cutting method is used to set up a block model by which the problem of complicated geometry shapes, such as hexahedron blocks can be solved. Theoretically, this method can be generally used for evaluating the stability of wedge-blocks with arbitrary geometric shapes. A software package based on above theory has been developed in the environment of Windows 3.x and Windows 95. As a typical example, the new theory and software have been applied to stability analysis of wedge slope at shiplock high slopes in Three-Gorges Project, the far hydropower station project in the world. It provides an efficient tool for quick judgment of unstable blocks, and ensure the safety of construction.